State of the Art
The present invention relates to ventilation systems used in indoor firing range enclosures for training in the firing of pistols and other firearms. More specifically, the present invention relates to a ventilation port and manifold which prevent bullet fragments from entering the ventilation system, reducing wear on fine particulate filters.
Field of Art
In order to maintain proficiency in the use of firearms, it is common for law enforcement officers, members of the military, and sportsmen to engage in target practice to improve or maintain their skills. However, indoor gun firing range enclosures present particularly difficult problems for proper ventilation because of the velocity of the bullets and the lead they contain.
Almost all of America's estimated 10,000 gun ranges permit the firing of lead-based bullets. Lead-based ammunition, however, can fragment into dust-sized particles upon impact with certain projectile traps, spreading toxic lead vapor and dust. High levels of lead exposure are known to cause a variety of health effects. The concentration of these contaminants must not be allowed to build up in the atmosphere of the shooting range, but due to regulations and general safety concerns, these contaminants cannot be released outside.
Thus, managing bullet fragments and dust is critical for shooting ranges. One method of reducing the production of lead dust is to deploy projectile traps adapted to lack curving internal surfaces. A bullet entering such a system is decelerated by the deflection of the bullet off plates, resulting in more bullet chunks and less dust, because the bullet does not ‘skid’ along an extended curving surface. Such skidding can strip layers of lead from the surface of the decelerating bullet, resulting in large quantities of fine lead dust.
Further, many ranges have adapted their equipment to draw air through the bullet trap and into filters, producing a negative air pressure not only within the trap, but often across the range as well. This ventilation system traps fine particles of dust in the filters, virtually eliminating dust accumulation in the bullet trap area. This improves safety for range workers who must remove and recycle spent bullets. The bullet-trap ventilation system also prevents dust-laden air from drifting back towards the shooters.
However, drawing air from the bullet trap and into filters can create further problems. Bullets ultimately may fragment into many small pieces during deceleration, producing fragments small enough to be carried by strong air flow. Some of these fragments may be drawn into the range's ventilation system, instead of falling into collector bins or channels. Thus the negative air pressure may unnecessarily pull lead from the trap that would otherwise be removed by a collection system at the bottom of the trap.
Once in the ventilation system, such fragments may become caught in the filters used to trap aerosolized lead or other metals, requiring frequent and costly filter replacement. The fragments may accumulate to the point of reducing airflow, requiring the ventilation system to be disassembled in order to remove them.
Heretofore, bullet traps have included various apparatuses for preventing lead and other fragments from passing through the traps and into the ventilation system. Some of the methods used include increasing stages of filtration, magnetized plates, and most often, long lengths of ventilation tubing which encourage the fragments to settle. These solutions, however, respectively require frequent maintenance, expensive mechanisms, and a great deal of space and periodic cleaning, and do not adequately solve the problem.